1. Field of the Invention
This invention relates to an ultrafine particle spraying apparatus suitable for forming a predetermined pattern or covering film on a surface of a predetermined article of metal, resin or the like.
2. Description of the Prior Art
As apparatus for spraying ultrafine particles, there is known an apparatus, as disclosed in Japanese patent application Sho No. 57-196085 filed by the applicant of this application, wherein innumerable ultrafine particles are conveyed under pressure by a carrier gas through a conveying pipe, and are sprayed onto a predetermined objective surface through a single nozzle pipe provided on a forward end of the conveying pipe. With this apparatus there may be formed a predetermined adhesion deposit of the ultrafine particles in the form of a point, line, surface, or the like.
This conventional apparatus, however, is such that when the ultrafine particles are sprayed onto the objective surface through the single nozzle pipe to form a line, the ultrafine particles are caused to strike against the objective surface and adhere thereto by the force of their own inertia while the carrier gas tends to spread outwardly and disperse. Accordingly, if the nozzle pipe is made large in caliber, i.e., internal diameter, since the carrier gas flows toward the circumference of the nozzle pipe, the ultrafine particles are liable to be scattered by a fringe flow of the carrier gas, and accordingly an outline of the drawn line tends to become blurred. Therefore, in general, the nozzle pipe to be used is preferably smaller than 1 mm in caliber and is usually 0.2-0.6 mm in caliber.
A distinct line can be drawn by the use of a nozzle pipe of such a proper caliber, but for drawing a thick line or a striped pattern comprising thick lines that are larger than 1 mm in width it is necessary to repeat the drawing procedure such that, after a single line is drawn by the nozzle, the nozzle is shifted laterally and is moved linearly along the preceding drawn line with or without leaving space. Additionally, it takes a long time and is troublesome in working and low in efficiency to form a covering film extending over almost the whole surface of an objective surface, and it is difficult in this case to obtain a film of uniform thickness. Thus, the conventional apparatus has various inconveniences as described above.
The present invention has as an object, therefore, to provide an apparatus for spraying ultrafine particles which is free from the foregoing inconveniences and which can draw a thick line or a striped pattern comprising thick lines or a complete covering film or the like on an objective surface with the ultrafine particles at a high efficiency.